Electric circuit breaker including stop means for limiting movement of a toggle linkage



Nov. 24, 1964 c. L. JENCKS ETAL 3,158,717

ELECTRIC CIRCUIT BREAKER INCLUDING STOP MEANS FOR LIMITING MOVEMENT OF A TOGGLE LINKAGE Flled July 18 1962 2 Sheets-Sheet 1 M O c 6 W1 INVENTORS C HARLES L. dENcKs, FRANK H. MURPHY BY ATTORNEY v Nov. 24, 1964 c. L. JENCKS ETAL 3,158,717

ELECTRIC CIRCUIT BREAKER INCLUDING STOP MEANS FOR LIMITING MOVEMENT OF A TOGGLE LINKAGE 2 Sheets-Sheet 2 Filed July 18, 1962 FIG. 3

II II E INVENTORS CHARLES L. dENcKs, FRANK H.MURPHY FIG.4-

ATTORNE Y supported by the side frames.

United States Patent 3,158,717 ELECTRIC CTRCUET BREAKER INCLUDING STOP MEANS FOR LEMITING MGVEMENT 0F A TOG- GLE LINKAGE Charles L. Jencks, Avon, and Frank H. Murphy, Hartford,

Conn., assignors to General Electric Company, a corporation of New York Filed July 18, 1962, Ser. No. 219,641 4 Claims. (Cl. 200116) Our invention relates to electric circuit breakers, and particularly to electric circuit breakers of the type including a contact arm operated by a pair of toggle links, the toggle links being supported on a releasable support or cradle.

In circuit breakers of the type described, it has been found that when the parts are constructed and arranged to provide maximum contact pressure in the closed position, it is necessary to provide means for maintaining the toggle links in at least a partially collapsed condition when tripping occurs. This is necessary to provide a desired bias force to move the breaker handle to a trip indicating position, and also to move the movable contact to a maximum open position.

In accordance with a particular prior arrangement, the toggle linkage has been provided with an extension adjacent the pivotal connection of the toggle linkage with the contact arms which extension is engageable with a stop carried by the mechanism side frame to perform this function. A mechanism of this type is shown and claimed in co-pending application S. N. 210,375, filed July 17, 1962, by Leonide P. Koval, and assigned to the same assignee as the present invention.

In accordance with the afore-mentioned prior construction, however, it is necessary to remove portions of the contact arm to provide clearance for the stops to be engaged by the toggle linkage, thus weakening the contact arm. In addition, in accordance with the prior con- .struction, it is necessary to provide stops extending inwardly from the mechanism side frames and cantilever- Such stops are subjected to forces tending to bend or tilt the stops with respect to their supported ends. It is therefore necessary, in the prior construction, to provide reinforcing means to support the said stops. This adds to the expense of the mechanism, as well as making it more diificult to assemble.

In addition, in accordance with the prior construction, the stops are located at a substantial distance from the pivot point of the contact arm. This produces an undesirable sliding action between the toggle linkage and the stops during the tripping operation and slows down the speed of movement of the parts during the tripping operation.

It is an object of the present invention to provide an electric circuit breaker of the type described including stop means which is stationary with respect to the mechanism frame which is substantially concentric with the pivot of the movable contact arm, whereby to avoid substantially all sliding friction therebetween.

It is another object of the invention to provide an electric circuit breaker of the type described including stop means mounted relatively stationary with respect to the mechanism frames which does not require the use of any parts other than those required for the basic circuit breaker mechanism.

It is another object of the invention to provide an electric circuit breaker of the type described including stop means relatively stationary with respect to the mechanism frame which is symmetrically supported with respect to the forces exerted thereon and does not require special reinforcing or supporting means.

In the invention, an electric circuit breaker is provided Patented Nov. 24, 1964 of the type described which includes a pivotally supported contact arm and means for operating the contact arm about its pivot, including a pair of interconnected toggle links. The toggle links are pivotally connected at one end to the contact arm and are pivotally connected at the other end to a releaseable support or cradle. The contact arm is adapted to be operated between open and closed positions by movement of a handle which carries one end of a tension spring, the other end of the tension spring being connected to the knee of the toggle linkage. In accordance with the invention in one form, the toggle links connected to the contact arm are provided with angular extensions which are disposed and arranged to engage the pivot pin of the contact arm when tripping occurs, whereby to maintain the toggle linkage in a partially collapsed position when tripping occurs.

The invention will be more fully understood from the following detailed description, and its scope will be pointed out in the appended claims.

In the drawings,

FIGURE 1 is a side elevation view, partially in section, of an electric circuit breaker constructed in accordance with the invention, portions of the casing being broken away, and the breaker being shown in the oif or reset condition;

FIGURE 2 is a view similar to FlGURE 1, showing the circuit breaker in the on or closed condition;

FIGURE 3 is a view similar to FIGURE 1, showing the parts in the tripped or automatically opened condition, and

FIGURE 4 is an end elevation view of the circuit breaker of FIGURE 1 taken generally on the line 4-4 of FIGURE 1.

Referring to FIGURE 1, the invention is shown as incorporated in an electric circuit breaker comprising an insulating casing including a base 2 and a cover 3. The casing is generally rectangular and includes three line terminals (not shown) at one end, and three load terminals (not shown) at the other end. Electrical continuity between each pair of corresponding line and load terminals is controlled by a pair of contacts including a relatively movable contact 4 and a stationary contact 5 (only one pair shown).

Each of the movable contacts 4 is carried by a movable contact support 6, which is pivotally connected to a contact arm '7 by pivot pin 14-. The forward end of the contact carrier 6 has a post 6A extending through the contact arm 7. A compression spring 6A is positioned on post 6A between the carrier 6 and the arm 7, and a cotter-pin 6B limits movement of the carrier 6 away from arm 7. The contact carrier 6 has a flexible connector 6C connected thereto adjacent the pivot pin 14 by suitable means such as by brazing. The contact arm 7 for the center pair of line and load terminals, illustrated in FIGURE 1, is pivotally supported on pin 8 carried by side plate portions of a stationary frame assembly 9. The contact arm 7 is generally channel-shaped throughout its major portion, and the pins 8 and 14 pass through depending side portions of the channel-shaped portion.

The contact arm 7 for each pair of line and load terminals is anchored by suitable fastening means 10 to a contact cross-arm 11. Movement of the center contact arm 7 therefore carries with it the two outside contact arms.

For the purpose of operating the center contact arm 7, together with the outside contact arms, between open and closed circuit positions, operating mechanism is provided including a toggle linkage comprising a sideby-side pair of upper toggle links 12., and a more widely spaced pair of lower toggle links 13. The lower toggle links 13 are pivotally connected to the opposed depending side portions of the contact arm 7 by the pivot pin 14.

The upper toggle links 12 are connected to the lower toggle links 13 by knee pivot pin 15. The upper toggle links 12 are also connected by a pivot pin 16 to a releasable support or cradle member 17.

The cradle member 17 is pivotally supported at one end on the support frame 9 by pivot pin 18. The cradle member 1'7 is releasably latched at its other end by a suitable latch member 19. The latch member 39 moves so as to release the cradle member 17 under the control of suitable current-responsive means, not shown.

The toggle linkage comprising links 12 and 13 is adapted to be operated between collapsed and straightened conditions by means of a manually operable handle member 20, carried by a handle support member 21. The handle support member 21 is generally bifurcated or U-shaped, and is pivotally supported on the sides of the frame member 9 on pivot supports 21A (see FIGURE 4).

lt iovement of the handle member 20 from the position shown in FIGURE 1 to the position shown in FIGURE 2 moves the operating spring 22, which is connected between the handle support member 21 and the knee pivot pin 15, across the line of centers of pivot pins 15 and 16, and moves the toggle linkage from collapsed position as in FIGURE 1 to straightened position as in FIGURE 2 with a snap action. This also moves the movable contact 4 to closed position as shown in FIGURE 2.

Upon the occurrence of predetermined current conditions through the contacts 4 and 5, the member 17 is released by the latch 19, and the parts thereupon move to the position shown in FIGURE 3.

For the purpose of maintaining the toggle links in a more collapsed position than they would otherwise assume when tripping occurs, the lower toggle links 13 are each made generally V-shaped, having an angularly extending arm 13A. The arm 13A is arranged at an acute angle with respect to the main toggle link 13 and has its end portion disposed and arranged to engage the pivot pin 8 which supports the contact arms 7 on the frame 9, when the parts move to tripped position as shown in FIGURE 3.

When the parts are in the closed or on position as shown in FIGURE 2, the arm 13A of the lower toggle link 13 is in contact with the pivot pin 8. In this position, the pin 8 acts as a stop to prevent the toggle linkage 12, 13 from going beyond the straightened or dead-center position more than a desired amount.

It will be observed that as the parts move from the closed or on position as shown in FIGURE 2, to the tripped position as shown in FIGURE 3, the end of the arm 13A remains in contact with the pin 8. It will be observed, moreover, that as the parts move from the closed position to the tripped position, the point of contact of the arm 13A with the pin 8 changes only very slightly, even though the angular position of the toggle link 13 changes substantially with respect to the pin 8. This is because the pin 3 is of relatively small diameter compared to the dimensions of the toggle link 13. In addition, the pin 8 is preferably made separate from both the frame 9 and the contact arm 7, whereby it is free to rotate with respect to these members. There is therefore no appreciable friction resistance opposing the movement of the parts, as they move from the closed to the tripped position.

Referring to FIGURE 4, it will be observed that pin 8 extends completely between the sides of the frame 9. The force exerted by the ends 13A of the toggle links 13 is therefore exerted symmetrically on the pin 8. The pin 8 can readily be made of such dimensions and material as to successfully withstand the repeated impact of the links 13A, which occurs, not only when tripping occurs, but also during normal manual operation of the circuit breaker, in which, as previously described, the pin 8 acts as a stop for the toggle linkage as it moves to straightened position.

It will be observed that the arm 13A of the toggle link 13 is approximately equal in length to the main portion of the link 13. This length is necessary in order for the extension to engage the pivot 8. At the same time, it will be seen, by reference to FIGURE I particularly, that the end of arm 13A, in the tripped position, does not extend an undesirable distance below the mechanism proper.

Since the mechanism is mounted on the bottom wall of the circuit breaker casing base 2, the clearance necessary to permit the movement of the end of arm 13A, determines the location of the bottom of the base 2.

In other words, the further that the end of the arm 13A extends below the mechanism in the tripped position, the greater must be the over-all depth of the base 2, and therefore, the over-all height of the casing. In accordance with the present invention, the arrangement of the parts is such that it is possible to extend the arm 13A to the length necessary to engage the pivot pin 8 without substantially increasing the depth of the base 2. It will be observed that there is provided, in accordance with the invention a circuit breaker having a mechanism of the type described including means for maintaining the toggle linkage in partially collapsed condition when tripping occurs, without the necessity of the addition of separate parts, and without the necessity of reducing the size, and therefore the strength, of the contact arm. It will also be observed that there has been provided in accordance with the invention a means for readily providing stop means for preventing the toggle linkage from moving beyond the dead center position.

While the invention has been shown in one particular embodiment, it will be readily appreciated that modifications thereof may readily be made by those skilled in the art, and it is therefore intended that the appended claims shall cover all such modifications as fall within the true spirit and scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit breaker comprising:

( a support,

(b)at least one movable contact arm pivotally supported on said support;

(0) operating means for operating said movable contact arm between open and closed circuit positions,

(d said operating means comprising a releasable toggle supporting member pivotally supported on said support,

(e) a pair of interconnected toggle links having one end pivotally connected to said movable contact arm and the other end pivotally connected to said releasable support,

(f) a handle member pivotally supported on said support,

(g) an operating spring having one end connected to said handle member and its outward end connected to the knee of said toggle linkage,

(h) latch means normally restraining said releasable toggle link support in latched position and operable in response to predetermined cunrent conditions to release said releasable toggle support,

(1) a pivot pin pivotally supporting said contact arm on said support, and

(j) said toggle linkage having means rigidly connected thereto engaging said pivot pin following release of said releasable means and maintaining said toggle linkage in a partially collapsed position.

2. An electric circuit breaker corn-prising:

(a) a. support,

(b) at least one movable contact arm pivotally supported on said support,

(0) operating means for operating said movable contact arm between open and closed circuit positions,

(d) said operating means comprising a releasable toggle supporting member pivotally supported on said support,

(e) a pair of interconnected toggle links having one end pivotally connected to said movable contact arm and the other end pivotally connected to said releasable support,

(1) a handle member pivotally supported on said sup- (g) an operating spring having one end connected to said handle member and its other end connected to the knee of said toggle linkage,

(h) latch means normally restraining said releasable toggle supporting member in latched position and operable in response to predetermined current conditions to release said releasable toggle supporting member,

(i) said portion of said toggle linkage which is connected to said contact arm including an angularly extending portion,

(j) a pivot pin pivotally supporting said contact arm on support, and

(k) said angular extension of said toggle linkage engaging said pivot pin upon release of said releasable means to maintain said toggle linkage in partially collapsed position following release of said releasable means.

3. An electric circuit breaker comprising:

(a) :a support,

(12) at least one movable contact arm pivotally supported on said support,

(c) operating means for operating said movable contact arm between open and closed circuit positions,n

ditions to release said releasable toggle supporting member,

(i) a pivot pin pivotally supporting said contact arm on said support,

(j) said toggle linkage having means rigidly connected thereto engaging said pivot pin and limiting the movement of said toggle linkage in contact closing direction, and

(k) said engagement of said toggle linkage with said pivot pin retaining said toggle linkage in a partially collapsed position following release of said releasable member.

4. An electric circuit breaker comprising:

(a) a support,

(b) at least one movable contact arm,

(0) a pivot pin pivotally supporting said contact arm on said support,

(d) a releasable toggle supporting member pivotally supported on said support,

(e) a pair of upper toggle links pivotally connected to said releasable toggle supporting member at one end,

(f) a pair of lower toggle links pivotally connected to said contact arm at one end thereof,

(g) a knee pin interconnecting said upper and lower pairs of toggle links,

(h) an operating spring having one end connected to said handle member and its other end connected to said knee pin of said toggle linkage,

(i) latch means normally restraining said releasable toggle supporting member in latched position and operable in response to predetermined current conditions to release said releasable toggle supporting member, and

(j) said lower toggle links including an angularly extending portion extending at an acute angle with respect to the main portion of said lower toggle links, said angularly extending portion being engageable with said pivot pin supporting said contact arm on said support, to provide a limit to movement of said toggle linkage in contact closing direction and also to maintain said toggle linkage in a partially collapsed condition following release of said releasable toggle supporting member.

References Cited in the file of this patent UNITED STATES PATENTS 3,003,046 De Torre oer. 3, 1961 

1. AN ELECTRIC CIRCUIT BREAKER COMPRISING: (A) A SUPPORT, (B) AT LEAST ONE MOVABLE CONTACT ARM PIVOTALLY SUPPORTED ON SAID SUPPORT; (C) OPERATING MEANS FOR OPERATING SAID MOVABLE CONTACT ARM BETWEEN OPEN AND CLOSED CIRCUIT POSITIONS, (D) SAID OPERATING MEANS COMPRISING A RELEASABLE TOGGLE SUPPORTING MEMBER PIVOTALLY SUPPORTED ON SAID SUPPORT, (E) A PAIR OF INTERCONNECTED TOGGLE LINKS HAVING ONE END PIVOTALLY CONNECTED TO SAID MOVABLE CONTACT ARM AND THE OTHER END PIVOTALLY CONNECTED TO SAID RELEASABLE SUPPORT, (F) A HANDLE MEMBER PIVOTALLY SUPPORTED ON SAID SUPPORT, (G) AN OPERATING SPRING HAVING ONE END CONNECTED TO SAID HANDLE MEMBER AND ITS OUTWARD END CONNECTED TO THE KNEE OF SAID TOGGLE LINKAGE, (H) LATCH MEANS NORMALLY RESTRAINING SAID RELEASABLE TOGGLE LINK SUPPORT IN LATCHED POSITION AND OPERABLE IN RESPONSE TO PREDETERMINED CURRENT CONDITIONS TO RELEASE SAID RELEASABLE TOGGLE SUPPORT, (I) A PIVOT PIN PIVOTALLY SUPPORTING SAID CONTACT ARM ON SAID SUPPORT, AND (J) SAID TOGGLE LINKAGE HAVING MEANS RIGIDLY CONNECTED THERETO ENGAGING SAID PIVOT PIN FOLLOWING RELEASE OF SAID RELEASABLE MEANS AND MAINTAING SAID TOGGLE LINKAGE IN A PARTIALLY COLLAPSED POSITION. 